1. Field of the Invention
The invention relates to a pair of toothed wheels that mesh with each other, and a transmission that is equipped with the toothed wheels.
2. Description of Related Art
There are known toothed wheels whose tooth faces are treated. For example, there are known toothed wheels having micro dimples that are formed by subjecting tooth faces of the toothed wheels to a shot peening treatment to cause high-hardness particles to collide with the tooth faces at high speed and thus plastically deforming the tooth faces slightly (see Japanese Patent Application Publication No. 2005-201295 (JP-2005-201295 A)). In addition, the related art documents associated with the invention include Japanese Patent Application Publication No. 09-302454 (JP-09-302454 A) and Japanese Patent Application Publication No. 2004-345022 (JP-2004-345022 A).
In the toothed wheels of Japanese Patent Application Publication No. 2005-201295 (JP-2005-201295 A), convexities are formed on each tooth face thereof. Thus, the lubrication state at the time when the toothed wheels are meshed with each other may be under the influence of the friction between the convexities thereof. Besides, in this case, the oil accumulated in the dimples may not be utilized. Thus, the toothed wheels of Japanese Patent Application Publication No. 2005-201295 (JP-2005-201295 A) may have a narrow operating region where the friction coefficient is low.